Users of printers desire the ability to estimate their cost of printing. One important factor is toner usage. Printer manufacturers typically estimate printed page cost based on a rough estimate of five percent toner coverage across a page. While this estimate can provide a comparison of the relevant costs of printing an image between different printers, the actual toner coverage between different printed pages can vary significantly from printer manufacturers' estimates. Therefore, the actual cost for a printed page can vary significantly for different print jobs. As such, there is a need to provide a method and apparatus to estimate toner usage for print jobs based on the image data from each job.
The number of toners used in print engines typically varies from one toner (monochrome printing) to four toners (cyan, magenta, yellow, and black) (commonly referred to as CMYK) to even six or more toners. The cost of consumables and printing processes can be significant, particularly for many color printers that use advanced toners or application techniques, such as for inkjet, thermal wax transfer or dye sublimation printers.
Printers typically receive PostScript™ and Printer Command Language (PCL) print jobs from an external device. These print jobs may include characters, regions of uniform color, 24 bit Red-Green-Blue (RGB) images and other object types. The raster image processor (RIP) in the printer scales these objects to device resolution (often 600 dots per inch), renders a bitmap at device bitdepth with the appropriate halftone screen and delivers the resulting bitmap to the print engine. The print engine generates commands to release toner upon a substrate to print a printed image, based upon the rendered bitmap of the page image. Toner is deposited and fixed onto the substrate, in a proportion relevant to the specified percentages of toner colors in the print job.